Abstract
OBJECTIVE: Point-of-care (POC) testing offers expedited results with lower blood volume requirements than central laboratory (CL) tests, particularly for low-birth-weight infants. METHODS: A retrospective cohort included 118 patients with paired POC and CL tests within one hour in the first 14 postnatal days. Differences and agreement were assessed using linear mixed-effect models that account for within and between-subject variations. RESULTS: Compared to CL, POC testing underestimated sodium (6.0 mEq/L), potassium (0.1 mEq/L), chloride (5.1 mEq/L), and glucose (2.3 mg/dL), and overestimated hemoglobin (0.08 g/dL) and hematocrit (0.8%). Differences (CL- POC) varied by postnatal age and sample type, with larger differences for sodium and chloride that decreased with age and smaller differences in capillary and venous than arterial samples. Glucose and hemoglobin differences increased over time, while hematocrit remained stable. CONCLUSIONS: POC results underestimated sodium, potassium, chloride, and glucose, and overestimated hemoglobin and hematocrit.